I use this. It's great.
Double batch @ 1050+ gravity (10 kilo grain bill) no problem. Could probably push 12 kilos... Probably even more if wheat grist (flour compacts better...).
Positives:
Light weight
Low footprint
No need for much internal plumbing except a pickup tube
Wide pot - easy to whirlpool with a paddle
Bottom of 40L holes are perfect size
Concerns:
Aluminium is only so robust, needs to not be kicked around.
Can't weld fittings on (unless you got an AC aluminium welder)
Lifting inner pot full of that grain is a 2 hand job, need assistant to place grate under it to drain on top of pot.
Volume management compared to separate vessels is a little hit and miss. Biabers don't worry about this.
In a nutshell - get it.